Antimicrobial compositions are used in a variety of automated processing and cleaning applications to reduce microbial or viral populations on hard or soft surfaces or in a body or stream of water. For example, antimicrobial compositions are used in various applications including kitchens, bathrooms, factories, hospitals and dental offices. Antimicrobial compositions are also useful in the cleaning or sanitizing of containers, processing facilities or equipment in the food service or food processing industries, such as cold or hot aseptic packaging. Antimicrobial compositions are also used in many other applications including but not limited to clean-in-place systems (CIP), clean-out-of-place systems (COP), washer-decontaminators, sterilizers, textile laundry machines, filtration systems, etc.
Whatever the application, an antimicrobial or “use” composition is a composition containing a defined minimum concentration of one or more active components which exhibit desired antimicrobial properties. One such category of active antimicrobial component are peracids, such as peroxycarboxylic acid (peracid), peroxyacid, peroxyacetic acid, peracetic acid, peroctanoic acid, peroxyoctanoic acid and others.
The concentration of active components in the use composition is chosen to achieve the requisite level of antimicrobial activity. In use compositions in which one or more peracids are the active component, and in the instance of a recirculating process, the concentration of hydrogen peroxide tends to increase over time while the concentration of peracid decreases. However, in order to maintain the requisite level of antimicrobial activity, the amount of peracid in the use composition must be maintained at a defined minimum concentration. In addition, as the amount of hydrogen peroxide in the use composition increases, the use composition may exceed a defined maximum concentration of hydrogen peroxide in the solution. In some applications, for example bottling line cleansing, the allowable amount of residual hydrogen peroxide is subject to government regulations. Once the hydrogen peroxide concentration exceeds the maximum concentration, the spent use composition is discarded and a new use composition generated.
To ensure that the amount of peracid is maintained at or above some minimum concentration and to determine when the amount of hydrogen peroxide reaches or exceeds a maximum concentration, it is necessary to determine the concentration of peracid(s) and hydrogen peroxide in the use composition. In the past, to determine both the peracid concentration and the hydrogen peroxide concentration in a use composition has required multiple time consuming manual titrations, several different reagents and relatively large volumes of use composition. Moreover, past devices and methods for determining both peracid and hydrogen peroxide concentrations were effective over only a narrow range of concentrations.